syconate

OK guys my XXXT started making a grinding noise and i assumed that it was the diff but after stripping down the diff it seemed fine, the motor is fine and both spur and pinion gears are fine. Anyone got any ideas?

Platinum_Racing

Check the spur again. If the teeth are warped it could make a strange sound. The idler gear and top gear could also be what's causing the noise. Check them all for stripage and replace any if neccesary. Reset the gear mesh and try again. If it still makes the noise, try adjusting the slipper clutch, or taking it apart to see if there's any dirt or grit in there.

briansid

Try to narrow it down. Turn the tires without the motor in and see you still hear the grinding. If not, put the motor in and line up the gear mesh. turn on the car and give it just a little gas to turn the tires slowly and see if you hear it then. Try it at different speeds.

If you hear without the motor in place, the problem is going to be in the diff somewhere. Completely break it down and clean everything. Inspect everything, too.

If you hear it with the motor in place, it is most likely the gear mesh. Check you spur gear and your pinion gear. Make sure the mesh isn't too tight. You want a little play.

If the spur gear looks good, check your motor plate. Take it off and hold it against a piece of glass to be sure it lines up straight. If it's off a bit it's bent and it will mess up your gear mesh. Replace the motor plate in that case. If it is the stock plate that comes on the RTR, it bends pretty easily. Get one of the anodized aluminum ones, but only if you have to replace the plate.

briansid

Platinum beat me to the punch.

Platinum_Racing

Sorry, I'm just good like that. You did add the info about the motor plete. I don't actually have a XXX-T, but I do have a XXX-NT, and I know the diffs in that truck absolutly suck, so I wouldn't be suprised if your diff was grinding.

JoshR 85

HeY!!!

it could be the motor... just last week someone had a chipped brushed n ran it n kept sounding worse and worse as he kept driving it till i told him to check the motor and rebuild it... or last problem that i cant think of is if you have an rpm gear cover i know that sometimes the spur gear will rub on them but mainly only on the T4's.....
hope this helps out n good luck findin the problem...

LaTa

briansid

The gear cover is a great point. I have an RPM gear cover and I had to cut sections on the top and bottom part of the cover so the spur gear wouldn't rub. I lost a spur gear every few weeks from grinding against the cover. The RTR uses a 88 tooth spur and that causes a major problem with the RPM covers. The 86 tooth doesn't do it near as much.

jbrow1

iTrader: (28)

Oops, wrong thread.

syconate

Thanks guys for the great info but i have gone over it twice and i am at a loss.
I rolled it back and forward without the motor in and everything felt smooth, i gave the motor a quick spin out of the truck and again it felt quite smooth, then when it was all back in i rolled the truck back and forward STILL SMOOTH!!! then i turned it on and gently gave it some throttle and not so smooth now!!!

I have replaced the spur with 86T Kevlar about 3 days ago and adjusted everything acordingly and it was running sweet.

I really am having some dramas with this thing!

Nate

Aaron Waldron

Is it a chirping noise? Or a legitimate "my tranny sounds like rocks in a blender" grinding?

Platinum - What don't you like about the diff? It shouldn't be any different than the diff in any other car you've had..I think Losi did a great job on the diff in our gas truck. Is there anything I can help you with, or help to make it better?

syconate

Its the rocks in a blender thing!

Carpy

I think I may have a similar problem. I have a Raptor 27 Truck and it starts first time, every time. NICE. So I start it up and rip it a while around the field. It then slows down and stops but the motor is still going. When I rev it it does'nt go, it sound like something is slipping inside. Carfully with the technical stuff because I have'nt a clue. HELP.
Thanks.

jbrow1

iTrader: (28)

Carpy, sometimes if you have a roasted diff, it'll work when it's cold. And you can't really tell if it's blown if you're not experianced with the mechanical side of rc yet because everything is pretty much locked together. But when it gets warm or hot the parts unlock and just spin. You probably have to take apart your tranny and see if that's the case. Best thing is to just use the manual and tear it down.

Aaron Waldron

If you hold the right rear tire and the spur gear with your right hand, and turn the left rear tire with your left hand, what happens? Any noises? Can you turn it?

syconate

ok, left wheel does not move when holding right rear and spur gear.